The echo printf command for Shell programming

Both Echo and printf in the shell can be used as output, and printf is an enhanced version of Echo

Show escape characters

echo \ "Abcdef\" "

>>> "ABCdef"

Show variables

Age=23

echo "My Age is $age"

>>>my name is 23

In the process of use, in order to avoid ambiguity, more use of ${age}

Show line breaks

echo "ok\n"

echo "My name is Liming"

>>>ok

>>>my name is Liming

Show Results Redirection

e Cho "My name is Limng" > file1

printf formats the output statement, but must be followed by a carriage return newline character, unlike Echo does not add

printf "acbdef\n"

>>>abcdef

>>>

# format-string is double quotes

$ printf "%d%s\ n" 1 "abc"

1 ABC

# single quotes are the same as double quotes

$ printf '%d%s\ n' 1 "abc"

1 ABC

# No quotation marks can also be output

$ printf %s abcdef

ABCdef

# The format specifies only one parameter, but the extra parameter is still output in that format, format-string is reused

$ printf %s ABC def

ABCdef

$ printf "%s\ n" abc def

Abc

Def

$ printf "%s%s%s\ n" A b c D e F g h i j

A b C

D E F

G h I

J# If there is no arguments, then%s is replaced with NULL,%d replaces with 0

$ printf "%s and%d \ n"

and 0

# If the string is displayed in%d format, then there will be a warning indicating an invalid number, at which point the default is 0

$ printf "The first program always prints '%s,%d\ n'" Hello Shell-bash: printf: Shell: Invalid Numbe

The first program is always prints ' hello,0 '

$

The echo printf command for Shell programming